pylibfdt: Convert to Python 3

Build this swig module with Python 3.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/scripts/dtc/pylibfdt/Makefile b/scripts/dtc/pylibfdt/Makefile
index 15e66ad..42342c7 100644
--- a/scripts/dtc/pylibfdt/Makefile
+++ b/scripts/dtc/pylibfdt/Makefile
@@ -21,7 +21,7 @@
 		CPPFLAGS="$(HOSTCFLAGS) -I$(LIBFDT_srcdir)" OBJDIR=$(obj) \
 		SOURCES="$(PYLIBFDT_srcs)" \
 		SWIG_OPTS="-I$(LIBFDT_srcdir) -I$(LIBFDT_srcdir)/.." \
-		$(PYTHON2) $< --quiet build_ext --inplace
+		$(PYTHON3) $< --quiet build_ext --inplace
 
 $(obj)/_libfdt.so: $(src)/setup.py $(PYLIBFDT_srcs) FORCE
 	$(call if_changed,pymod)
diff --git a/scripts/dtc/pylibfdt/libfdt.i_shipped b/scripts/dtc/pylibfdt/libfdt.i_shipped
index 76e61e9..53b70f8 100644
--- a/scripts/dtc/pylibfdt/libfdt.i_shipped
+++ b/scripts/dtc/pylibfdt/libfdt.i_shipped
@@ -624,7 +624,7 @@
         Raises:
             FdtException if no parent found or other error occurs
         """
-        val = val.encode('utf-8') + '\0'
+        val = val.encode('utf-8') + b'\0'
         return check_err(fdt_setprop(self._fdt, nodeoffset, prop_name,
                                      val, len(val)), quiet)
 
diff --git a/scripts/dtc/pylibfdt/setup.py b/scripts/dtc/pylibfdt/setup.py
index 4f7cf04..992cdec 100755
--- a/scripts/dtc/pylibfdt/setup.py
+++ b/scripts/dtc/pylibfdt/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 
 """
 setup.py file for SWIG libfdt